Abstract:

An apparatus for controlling valve displacement of an internal combustion
engine comprises a rocker arm having a first arm portion and a second arm
portion, said rocker arm being pivotable about a pivot interposed between
said first and second arm portions. The apparatus further comprises an
actuation arrangement adapted to actuate said first arm portion of said
rocker arm and a valve arrangement adapted to be actuated by said second
arm portion of said rocker arm. A damper arrangement is pivotably
connected to said first arm portion and adapted for damping movement of
said rocker arm around said pivot.

Claims:

1. An apparatus for controlling valve displacement of an internal
combustion engine comprising:a rocker arm having a first arm portion and
a second arm portion, said rocker arm being pivotable about a pivot
interposed between said first and second arm portions;an actuation
arrangement adapted to actuate said first arm portion of said rocker
arm;a valve arrangement adapted to be actuated by said second arm portion
of said rocker arm;a damper arrangement pivotably connected to said first
arm portion and adapted for damping movement of said rocker arm around
said pivot.

2. The apparatus according to claim 1, wherein:the actuation arrangement
comprises a push rod adapted to be reciprocated, andthe first arm portion
extends from the pivot to a first free end of the rocker arm and the
second arm portion extends from the pivot to a second free end of the
rocker arm opposite the first free end, wherein the first arm portion of
the rocker arm is adapted to be driven by reciprocating movement of said
push rod.

3. The apparatus according to claim 2, wherein:said valve arrangement
comprises a valve actuation bridge adapted to be driven by said second
arm portion of said rocker arm, said valve actuation bridge being
connected to valve shafts of said valves, andsaid valve arrangement
comprises inlet and/or exhaust valves.

4. The apparatus according to claim 3, whereinsaid rocker arm is pivotable
about said pivot in a first rotating direction and a second rotating
direction which is reverse to the first rotating direction;said damper
arrangement is hydraulically operated by means of a hydraulic fluid, the
damper arrangement being pivotably connected to said first arm portion so
that movement in said first rotating direction of said rocker arm around
said pivot is damped and during movement in said second rotating
direction of said rocker arm said hydraulic fluid is sucked.

5. The apparatus according to claim 4, whereinsaid damper arrangement is
adapted to apply a pushing force to said first arm portion of said rocker
arm for damping the rotation movement of said rocker arm in said first
rotational direction during closing of said inlet and/or exhaust valves,
andsaid damper arrangement is adapted to suction said hydraulic fluid
during the rotation movement of said rocker arm in said second rotational
direction during the opening of the inlet and/or exhaust valves.

6. The apparatus according to claim 4, whereinthe damper arrangement is
adapted to apply a tensile force to the first arm portion of the rocker
arm for damping the rotation movement of said rocker arm in said first
rotational direction during closing of the inlet and/or exhaust valves,
andthe damper arrangement is adapted to suction said hydraulic fluid
during the rotation movement of said rocker arm in said second rotational
direction the opening of the inlet and/or exhaust valves.

7. The apparatus according to claim 6, wherein:the damper arrangement
includes a housing, a piston having a piston rod and being displaceably
arranged in the housing and a fluid chamber formed by the housing and the
piston and adapted to be filled with a pressurized fluid, andthe piston
rod is pivotably attached to the first arm portion of the rocker arm.

8. The apparatus according to claim 7, wherein said housing is an integral
part of a cylinder head of the internal combustion engine.

9. The apparatus according to claim 8, further comprising a forked lever
having a base and a pair of fork parts, the forked lever connecting the
piston-rod to the first arm portion of the rocker arm, the base of the
forked lever being pivotably connected to the piston-rod and the fork
parts of the forked lever being pivotably connected to the first arm
portion of the rocker arm.

10. The apparatus according to claim 9, wherein:said push-rod includes a
gap-compensating telescoping device, said first arm portion of the rocker
arm being driven by said push rod via the gap-compensating telescoping
device, and optionally, said gap-compensating telescoping device is
integrated in said push-rod.

11. The apparatus according to claim 1, further comprising a
shut-off/passage valve, a throttle and a check valve arranged in parallel
with each other, wherein a first connection of the shut-off/passage
valve, a first connection of the throttle and a first connection of the
check valve are in fluid communication with said fluid chamber via a
first oil-supply line, and wherein a second connection of the
shut-off/passage valve, a second connection of the throttle and a second
connection of the check valve are in fluid communication with an oil
supplying system via a second oil-supply line.

12. A method of controlling at least one combustion chamber valve
associated with a rocker arm, the method comprising:applying a force to a
first arm portion of said rocker arm for rotating said rocker arm about a
pivot interposed between said first arm portion and a second arm portion,
said second arm portion being adapted to actuate at least one combustion
chamber valve, anddamping rotation of said rocker arm using a damper
arrangement pivotably connected to said first arm portion of said rocker
arm.

13. The method of claim 12, wherein said damper arrangement is
hydraulically operated by means of a hydraulic fluid, said method further
comprising:rotating said rocker arm about said pivot in a first rotating
direction and simultaneously applying a force to said first arm portion
of said rocker arm so that movement of said rocker arm around said pivot
in said first pivoting direction is damped, androtating the rocker arm
about said pivot in a second rotating direction which is reverse to said
first rotating direction and simultaneously sucking said hydraulic fluid.

14. The method according to claim 13, wherein the step of closing of said
combustion chamber valve is delayed by said damper arrangement.

15. The method according to claim 14, wherein a compressive force or a
tensile force is applied to said first portion of the rocker arm, thereby
delaying pivoting movement of the rocker arm in a valve-closing
direction.

16. An internal combustion engine having an apparatus for controlling
valve displacement of said internal combustion engine, wherein the
apparatus comprises a rocker arm, said rocker arm being pivotable about a
pivot interposed between first and second arm portions, an actuation
arrangement for applying a force to said first arm portion of said rocker
arm, a valve arrangement actuated by said second arm portion of said
rocker arm and a damper arrangement pivotably connected to said first arm
portion and damping a movement of said rocker arm around said pivot.

Description:

CROSS-REFERENCE

[0001]The present application claims priority to European patent
application No. 07021291.5, filed 31 Oct. 2007, which is incorporated
herein by reference as if fully set forth herein, and is the national
stage of PCT/EP2008/009183, filed Oct. 30, 2008.

TECHNICAL FIELD

[0002]The present disclosure relates to an apparatus for controlling valve
displacement of an internal combustion engine and, more particularly, to
an apparatus for adjusting or delaying the closing of inlet valves of an
internal combustion engine, in particular diesel and gasoline engines.

BACKGROUND

[0003]In order to reduce NOx emissions from diesel and gasoline engines,
it is known to use the "Miller process" to cool or reduce the combustion
temperature. According to this process, a cooling effect is achieved by
closing the intake valves very early. The subsequent expansion of the
volume of gas in the combustion chamber lowers the temperature of the
fresh gas mixture and the cylinder filling loss of the charged engine is
compensated by an increased charging pressure generated by a
turbocharger.

[0004]For transient engine conditions, in which the loaded engine must
generate increased power/torque within a short time, shutting-off the
Miller process is very helpful. This can be achieved by displacing the
inlet cam profile by rotating the cam shaft relative to the crankshaft or
by displacing the cam on the cam shaft or by modifying the coupling of
the cam/valve. In all cases, a valve-opening overlap and thus evacuation
of the cylinders is reduced by displacing the cam profile.

[0005]In EP 1 477 638 A1A, a device for variably controlling the opening
and/or closing of inlet and/or exhaust valves of an internal combustion
engine of the above-mentioned type is disclosed. This known device is
adapted to delay the closing of inlet valves of an internal combustion
engine, and includes a damping device integrated in a guide rod for
guiding a valve actuation bridge during its up and down motion. Hence,
the damping device is an integrated part of the valve actuation bridge.
More particularly, in this known device, an annular recess is disposed
between a guide rod of a piston and a cylinder sleeve. The annular recess
is in fluid communication with an axial bore axially extending within the
guide rod via a transverse bore. One end of a tap bore opens or
discharges into the axial bore of the guide rod. The other end of the tap
bore is in fluid communication with valve units via oil-supply lines.
More particularly, the tap bore is connectable with a lubricating
oil-supply port as a function of the valve position of the gas exchange
valves either via a first oil-supply line controlled by a valve unit,
which includes a passage and shutoff valve, or via a second oil-supply
line controlled by a second valve unit, which includes a one-way valve
and a throttle. Thus, controlling of the gas exchange valves as a
function of the closed position and/or the opened position can be
achieved by means of the valve units having the correspondingly-designed
valves.

[0006]When the gas exchange valves are closed, lubricating oil contained
in the annular recess can be supplied into a further valve unit via the
axial bore and the tap bore, as well as via an oil-supply line. In
addition, when the valve is closed, the lubricating oil can be supplied
into the valve unit having the throttle so that the intake valves will
assume a delayed position. In contrast, when the gas exchange valves are
in a delayed position, the free or terminal end of the rocker arm that is
opposite of the valve actuation bridge is pivoted about the rotational
axis towards the rocker arm by means of a telescoping member, which is
spring-biased and guided in the push-rod, without any play or clearance
therebetween.

[0007]However, the device disclosed in EP 1 477 638 A1 requires
construction space between the two inlet and/or exhaust valves and its
associated springs. Furthermore, due to the integration of the damping
device in the guide rod of the valve actuation bridge, the known device
requires a guide rod.

[0008]U.S. Pat. No. 3,520,287 discloses an exhaust valve control for an
engine braking system which also includes an arrangement having a guide
rod slidably mounted on a valve actuation bridge. The valve actuation
bridge and the guide rod together define a hydraulic chamber that expands
when the valve bride advances to open the exhaust valves and contracts
when the valve actuation bridge retracts to permit the two exhaust valves
to be closed by the exhaust valve springs. Again, a damping device is
integrated into the guide rod and is part of the valve actuation bridge.
Hence, like the above arrangement, a construction space between the two
valves is necessary and this known assembly requires a guide rod.

[0009]U.S. Pat. No. 6,905,155 discloses an apparatus for limiting the
travel of a slave piston in a slave piston cylinder in a compression
release engine retarder. The apparatus is connected to a hydraulic
circuit and an internal passageway is defined in the slave piston head.
The internal passageway comprises a vertical bore, a horizontal bore and
an annular channel which together define a path for bleeding off the
pressure at the top of the slave piston when the annular channel and an
aperture in the slave piston cylinder are aligned. By bleeding off the
hydraulic pressure at top of the slave piston, the motion of the slave
piston is restricted to a desired stroke. The apparatus includes a
locking adjustable foot on the slave piston stem which provides a means
for adjusting the lash. Here, the known arrangement for actuating at
least one engine valve requires a minimum space above the valve actuation
bridge and the rocker arm.

[0010]US 2005/0121008 A1 discloses a method and apparatus for controlling
a temperature in a combustion cylinder in an internal combustion engine.
A rocker arm is located to move about a pivot. A push-rod provides a
mechanical force against the rocker arm. An electro-hydraulic assist
actuator may include a plunger assembly for providing a hydraulic force
used to vary the open duration of an intake valve. In particular, the
electro-hydraulic assist actuator may be used to hold the intake valve
open for a period of time longer than a cam is designed to do. The
plunger assembly may be located at the same side of the rocker arm as the
push rod. In addition, the plunger assembly is designed to provide a
mechanical force during a first rotating direction of the rocker arm. A
reverse rotating direction of the rocker arm has no impact on the plunger
assembly. Consequently, the known plunger assembly may be relatively slow
and the reaction time could be relatively long.

[0011]US 2003/0221644 A1 shows a similar engine valve actuation system
including a fluid actuator configured to selectively prevent an intake
valve from moving in a first position.

[0013]The present disclosure is directed, at least in part, to improving
or overcoming one or more aspects of prior devices and methods for
controlling valves and, more particularly, of apparatus for adjusting or
delaying the closing of inlet valves of an internal combustion engine.

SUMMARY OF THE DISCLOSURE

[0014]According to a first exemplary aspect of the present teachings, an
apparatus for controlling valve displacement of an internal combustion
engine comprises a rocker arm having a first arm portion and a second arm
portion, said rocker arm being pivotable about a pivot interposed between
said first and second arm portions. Said apparatus further comprises an
actuation arrangement adapted to actuate said first arm portion of said
rocker arm and a valve arrangement adapted to be actuated by said second
arm portion of said rocker arm. A damper arrangement may be pivotably
connected to said first arm portion and adapted for damping movement of
said rocker arm around said pivot.

[0015]In a further exemplary embodiment of the disclosed apparatus said
rocker arm may be pivotable about the pivot in a first rotating direction
and a second rotating direction which is reverse to the first rotating
direction. Said damper arrangement may be hydraulically operated by means
of a hydraulic fluid and pivotably connected to said first arm portion so
that movement in said first rotating direction of said rocker arm around
said pivot is damped and during movement in said second rotating
direction of said rocker arm said hydraulic fluid is sucked. The suction
of the hydraulic fluid may be caused by the movement in said second
rotating direction of said rocker arm and the pivotable or articulated or
hinged connection of the damper arrangement to the rocker arm.

[0016]A further exemplary embodiment may comprise a push-rod adapted to be
reciprocated, e.g. by a valve cam and a rotational drive, a rocker arm
pivotable about a rotational axis, a valve actuation bridge and a damper
arrangement adapted to damp the pivoting motion of the rocker arm during
movement of valves, preferably during a closing of one or more of the
engine valves. In this exemplary embodiment a first arm portion of the
rocker arm extends from the rotational axis to a first free end of the
rocker arm and a second arm portion of the rocker arm extends from the
rotational axis to a second free end of the rocker arm opposite the first
free end. The first arm portion of the rocker arm may be driven by the
push-rod. The valve actuation bridge may be driven by the second arm
portion of the rocker arm and may connect to respective valve shafts of
the valves. The damping device acts on the first arm portion of the
rocker arm driven by the push-rod. The valves may comprise one or more
inlet valves and/or one ore more outlet valves. In one exemplary
embodiment of the present teaching the damper arrangement causes a delay
of the closing of inlet valves.

[0017]According to another exemplary aspect of the present teachings, a
method of controlling at least one combustion chamber valve associated
with a rocker arm may comprise rotating said rocker arm about a pivot
interposed between first and second arm portions for actuating at least
one combustion chamber valve and damping the rotation of said rocker arm
with a damper arrangement jointly connected to said first portion of said
rocker arm. According to a further exemplary embodiment of the disclosed
method, the method may further comprise rotating said rocker arm about
said pivot in a first rotating direction and simultaneously applying a
force to said first arm portion of said rocker arm so that movement of
said rocker arm around said pivot in said first pivoting direction is
damped. Rotating the rocker arm about said pivot in a second rotating
direction which is reverse to said first rotating direction may cause
sucking said hydraulic fluid.

[0018]According to another exemplary aspect of the present teachings, a
method of controlling at least one combustion chamber valve associated
with a rocker arm may comprise rotating said rocker arm about a pivot
interposed between first and second arm portions for actuating at least
one combustion chamber valve and damping rotation of said rocker arm with
a damper arrangement connected to said first portion of said rocker arm.

[0019]According to another exemplary aspect of the present teachings, an
internal combustion engine comprises an apparatus for controlling valve
displacement of said internal combustion engine. Said apparatus includes
a rocker arm, said rocker arm being pivotable about a pivot interposed
between first and second arm portions. Furthermore, an actuation
arrangement for applying a force to said first arm portion of said rocker
arm and a valve arrangement actuated by said second arm portion of said
rocker arm are comprised. Finally, a damper arrangement is pivotably
connected to said first arm portion and damps a movement of said rocker
arm around said pivot.

[0020]As utilized herein, the terms "damping unit" and "damper
arrangement" or similar terms used throughout the description are
intended to cover any kind of apparatus/device that imparts a resistive
decelerating force to the reciprocating movement of any kind of valves.

[0021]Representative, but not limiting, examples of suitable damper
arrangements in accordance with the present teachings may include
hydraulic and pneumatic cylinders, such as e.g. utilized for shock
absorbing applications. In some embodiments, a spring or other resilient
elastic materials or devices may be suitably utilized, particularly, if
the elastic return force can be changed in operation.

[0022]Other features and aspects of this disclosure will be apparent from
the following description and the accompanying drawings.

[0023]It is to be understood that forgoing general description and the
following detailed description are exemplary and explanatory only and are
not restrictive of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]The accompanying drawings, which are incorporated in and constitute
a part of the specification, illustrate an exemplary embodiment of the
disclosure and, together with the description, serve to explain the
principles of the disclosure. In the drawings,

[0025]FIG. 1 is a schematic illustration of a first preferred exemplary
device for variably controlling the closing of inlet and/or exhaust
valves of an internal combustion engine;

[0026]FIG. 2 is a schematic diagram of the hydraulic system connected to a
damping unit as part of the exemplary device for variably controlling the
closing of inlet and/or exhaust valves shown in FIG. 1;

[0027]FIG. 3 is a perspective view of a second exemplary device for
variably controlling the closing of inlet and/or exhaust valves of an
internal combustion engine;

[0033]Reference will now be made in detail to the exemplary embodiments of
the present teachings, examples of which are illustrated in the
accompanying drawings. Wherever possible, the same reference numerals
will be used throughout the drawings to refer to the same or like parts.

[0034]Referring to FIG. 1, an exemplary device 100 for variably
controlling the opening and/or closing of inlet and/or exhaust valves 180
of an internal combustion engine (not shown), for example, a four-stroke
diesel engine, is provided. The valve control device 100 may include a
rocker arm 110 that may be rotatable about a rotational axis 115. The
rocker arm 110 has a first arm portion 111 extending from the rotational
axis 115 to a first free end 112 of the rocker arm 110, and a second arm
portion 113 extending from the rotational axis 115 to a second free end
114 of the rocker arm 110. The second free end 114 is opposite the first
free end 112 of the rocker arm 110.

[0035]In addition, the valve control device 100 may include an actuation
arrangement. This actuation arrangement may comprise a push-rod 120. A
free end 128 of the push-rod 120 may be in contact with the free end 112
of the rocker arm 110. The push-rod 120 may be driven by any arrangement.
In one exemplary embodiment the push-rod 120 may be driven by a valve cam
(not shown) and a rotational drive (not shown). However, since such a
drive device for of the push-rod 120 is well known, a detailed
explanation of this kind of drive device is omitted.

[0036]As shown in FIG. 1, a valve actuation bridge 160 may be in contact
with the second free end 114 of the rocker arm 110. The valve actuation
bridge 160 may have a guide rod 170 for guiding the valve actuation
bridge 160 during up-and-down reciprocating motion for opening and/or
closing the inlet and/or exhaust valves 180. The valve actuation bridge
might be omitted if e.g. only one valve is to be actuated.

[0038]Furthermore, the valve control device 100 may include a damper
arrangement or damping unit 130 for applying a damping force to the first
rocker arm portion 111 of the rocker arm 110 during pivoting of the
rocker arm 110 in a first pivoting direction shown by arrow 210. By
pivoting of the rocker arm 110 in the first pivoting direction of the
arrow 210, the valves 180 may be forced towards their respective valve
seats 191 (see FIG. 5) and therefore in the direction for closing the
valves 180. The arrow 215 illustrates a second pivoting direction of the
rocker arm 110 about the rotational axis 115 for opening the valves 180,
i.e. the valve discs 190 move away from their respective valve seats 191.
The damping unit 130 may include a piston 145 having a piston-rod 150. In
one exemplary embodiment the piston 145 is slidably supported in a
housing 146. The piston 145, in combination with the housing 146, may
define a fluid chamber 140 which is in fluid communication via an
oil-supply line 305 with a hydraulic system 300 schematically shown in
FIG. 2.

[0039]In FIGS. 2 and 3, one exemplary embodiment the hydraulic system 300
is schematically shown. This hydraulic system 300 may be in fluid
communication with the damping unit 130 of FIG. 1. The hydraulic system
300 may include a control valve or shut-off valve 310, an throttle 315
and a check valve 320. This elements 310, 315 and 320 may be arranged in
parallel by fluid supply lines 305, 330. In one exemplary embodiment the
fluid supply lines 305, 330 may be adapted to supply oil and the throttle
315 may be adapted to be adjustable. As was already mentioned above, the
supply line 305 may end in the fluid chamber 140 of the damper
arrangement 130. The supply line 305 may also connect with the shut-off
valve 310. In one exemplary embodiment the shut-off valve 310 may
comprise a solenoid valve. It may be in fluid communication via the
supply line 330 with a supply system 350 of the internal combustion
engine. In one exemplary embodiment the supply system 350 may comprise a
lubricating oil system.

[0040]The throttle 315 may connect with the supply line 305 and the
oil-supply lines 330 and 340. The check valve 320 may also connect with
the supply lines 305, 330 and may be arranged parallel to the throttle
315. Hence, the fluid, e.g. oil, can flow into a collecting reservoir 335
via a bleed line (also denotes as "blood-line"). The bleed line may be
connected to the supply lines 330, 340. Finally, the supply lines 305,
330 and, hence, the valve 310, the throttle 315 and the check valve 320
are connected via the oil line 340 with e.g. the engine lubrication oil
system 350 as is schematically illustrated. In FIG. 3 an lubricating oil
inlet and outlet port 340 are shown.

[0041]Referring now to FIGS. 3-8, an exemplary embodiment of a valve
control device 100 is explained in more details.

[0042]As shown in FIGS. 3 to 5, the device 100 includes the push-rod 120
having a connecting part 122, a telescoping device 124 for
gap-compensating and a hollow rod member 126 closed by a cap 128.
Referring to FIG. 5, further details of the telescoping member 124 of the
push-rod 120 will now be explained. In one exemplary embodiment, a rod
part of the push-rod 120 is integral with the rod member 126 of the
push-rod 120. The outer diameter of the rod part may be greater than the
outer diameter of the rod member 126 for accommodating a cylindrical
sleeve 125, which receives a helical spring 127 and a cap 123. The spring
127 may rest on a ring-shaped projection 121 of the cylindrical sleeve
125. On the opposite side of the helical spring 127, the helical spring
127 urges against the cap 123. The outer end of the cap 123 may be
hemispherical. Due to the telescoping device 124, any gap or play
occurring during pivoting of the rocker arm 110 may be compensated.

[0043]As shown in FIG. 3, in one exemplary embodiment two valve bridges
160 are pivotably arranged above a cylinder head 101 having an air inlet
102 and a connecting flange 103 for mounting the cylinder head 101 at an
engine housing (not shown). For illustration purposes, only one push-rod
120 is shown. However, the second rocker arm 110 may be, like the first
rocker arm 110, adapted to be driven by a push-rod 120. The second rocker
arm 110 acts on a further valve actuation bridge (not shown) which
contacts a pair of outlet valves (not shown). The second rocker arm 110
may also preferably include a damping device 130 like the first rocker
arm 110 as shown in FIG. 3.

[0044]The first rocker arm 110 may be pivotably arranged about an axis 115
and its free end 114 may contact the valve actuation bridge 160. As can
be seen in FIGS. 3 and 4 and, in particular in FIG. 5, in one exemplary
embodiment two inlet valves 180 are adapted to rest on the respective
seat 191 in the cylinder head 101. Each valve shaft 185 may be biased
upwards by a valve spring 165. The arrangement of the valves 180 and
their respective contacts with the valve actuation bridge 160 is
basically known and therefore, a detailed explanation thereof is omitted.

[0045]The damping unit 130 shown in FIGS. 3-8 includes in one exemplary
embodiment a guiding sleeve 146 sealingly arranged in the piston housing
143. The piston-rod 150 may extend through the guiding sleeve 146 and may
be adapted to reciprocate within the guiding sleeve 146. A seal 151
arranged in the inner circumference of the guiding sleeve 146 may contact
the outer surface of the piston-rod 150 such that an oil-leakage is
prevented. As shown for example in FIG. 6, a joint 410 may be provided on
the end 152 of the piston-rod 150. At this joint 410, a forked lever 400
may be rotatably connected to the piston-rod end 152. The forked lever
400 may have two fork parts 411. A bearing member 117 of the rocker arm
110 may be arranged between the two spaced apart fork parts 411. At this
point, a joint connection 405 may be provided between the rocker arm 110
and fork parts 411. Due to this arrangement, the reciprocating motion of
the piston-rod 150 may be transferred to the rocker arm 110 such that the
rocker arm 110 rotates about the rotational axis 115.

[0046]A more detailed illustration of the assembly of the damping unit 130
and the rocker arm 110 is provided in FIGS. 6-8. As shown, in one
exemplary embodiment the piston housing 143 includes the guiding sleeve
146. The end of the piston-rod 150 may extend through the guiding sleeve
146. The forked lever 400 may be rotatably connected to the end of the
piston-rod 152 as well as to the first arm portion 111 of the rocker arm
110. In FIGS. 6 and 8, the contacting members 116 of the two rocker arms
110 are shown, which contacting members 116 may contact the push-rod 120
(see FIGS. 1, 3 and 4). The second free end 114 of the second arm portion
113 may have a contacting member 161, which in one exemplary embodiment
is part of the rocker arm 110 or of the valve actuation bridge 160.

INDUSTRIAL APPLICABILITY

[0047]Referring to FIGS. 1 and 2, an exemplary embodiment of a method for
operating the exemplary embodiment of an apparatus 100 for variable
controlling at least one engine valve 180 shown e.g. in FIGS. 3-8 will
now be explained.

[0048]During normal operation, the push-rod 120 is actuated by a valve cam
and a rotational drive (both not shown), thereby rotating the rocker arm
110 around the rotational axis 115. During the upward movement of the
push-rod 120, the rocker arm 110 is urged to rotate around rotational
axis 115 as indicated by arrow 215. As a result, the valve actuation
bridge 160, which is vertically movably supported by the guide rod 170,
is being pivotably displaced or rotated against the biasing force of the
valve springs 165 and the two intake valves 180 open in parallel, i.e.
the valve discs 190 move away from the respective valve seats 191, as
shown in FIG. 5. Consequently, during the downward movement of the valve
actuation bridge 160, the piston-rod 150 of the damping unit 130 is urged
to move upwards due to the joint connection with the first arm portion
111 of the rocker arm 110 via the forked lever 400. At the same time, the
volume of the fluid chamber 140 increases and pressurized motor
lubricating oil fills this increasing volume in an unthrottled manner via
the oil-supply line 305 and the shut-off/passage valve 310, because the
check valve 320 is opened in the filling direction and the
shut-off/passage valve 310 is in the position shown in FIG. 2. As a
result, the pivoting of the rocker arm 110 in the direction indicated by
arrow 215 may not delayed. In particular, the positive connection, e.g.,
the pivot connection or hinge connection with the rocker arm 110 via,
e.g., the lever 400 may generate a suction effect in the fluid chamber
140 for at least assisting the filling process of the fluid chamber 140
with fluid. Consequently, the filling process of the chamber with
hydraulic fluid may be improved. In another exemplary embodiment the
pivoting of the rocker arm 110 in the direction indicated by arrow 215
may be delayed with the aid of the damper arrangement 130.

[0049]The biasing force of the valve springs 165 may cause the valves 180,
the valve actuation bridge 160, the rocker arm 110, the push-rod 120 to
remain in series connection during this time.

[0050]The closing of the intake valves 180 may be initiated when the
not-illustrated rotational drive and the push-rod 120 move downward in
accordance with the further rotation of the not-illustrated cam profile.
At this time, the valve actuation bridge 160 may be displaced upward by
e.g. the biasing force of the valve springs 165, whereby the volume in
the fluid chamber 140 may be reduced and the lubricating oil located in
the fluid chamber 140 is discharged to the lubricating oil-supply system
350 via the oil-supply lines 305 and 340 in an unthrottled throttle
manner via the opened shut-off/passage valve 310. On the other hand, when
the shut-off/passage valve 310 is closed, i.e. in the shut-off position
during the closing motion of the intake valves 180, the discharge of the
lubricating oil from the fluid chamber 140 no longer takes place in an
unthrottled manner via the shut-off/passage valve 310. Instead, the
lubricating oil may be discharged via the throttle 315. Consequently, the
upward movement of the valve actuation bridge 160 may be hindered, damped
or delayed because the cross section of the throttle 315 is restricted.
As a result, in one embodiment the upward stroke of the valve actuation
bridge 160 and, consequently, the closing of the intake valves 180 may be
damped/delayed by e.g. reducing the throttle cross section of the
throttle 315.

[0051]Due to the arrangement and construction explained above and shown in
the figures, in one exemplary embodiment a predetermined damping of the
closing of the inlet and/or exhaust valves 180 can be achieved. Contrary
to the known art, in which the delay device is integrated in the valve
actuation bridge and the associated guide rod, the presently preferred
embodiment maybe used for e.g. two and/or e.g. four valve cylinder heads
with or without a guide-rod because in one exemplary embodiment the
damper arrangement is disposed on the same side of the rocker arm 110 as
the push-rod 120. Therefore, in one exemplary embodiment the damper
arrangement 130 may be installed independently of the structure and
design of the valve actuation bridge. A further advantage may be that
maintenance of the valve control devices 100 is easier than of prior art
devices, because in one exemplary embodiment for example the damper
arrangement may be replaced without substantial disassembly.

[0052]Although the preferred embodiments of this disclosure have been
described herein, improvements and modifications may be incorporated
without departing from the scope of the following claims.